Description
Dwyer 1638-5 Large Diaphragm Pressure Switch Overview
The Dwyer 1638-5 is a large diaphragm pressure switch engineered for reliable differential pressure sensing in HVAC, building automation, and light industrial applications. Designed to work with air and non-combustible gases, this switch delivers accurate, repeatable switching performance across a broad range of system pressures.
Key Features
- Large diaphragm design for enhanced sensitivity and reliable actuation at low pressure differentials
- Set point range: 2″ w.c. to 6″ w.c. (inches water column)
- Approximate deadband: 0.07 to 0.25″ w.c. for tight, consistent switching
- Compatible media: air and non-combustible gases
- SPDT (Single-Pole, Double-Throw) switch for versatile circuit control — supports both normally open and normally closed configurations
- 1/8″ Female NPT pressure connection for easy installation with standard fittings
Specifications
- Model: 1638-5
- Brand: Dwyer Instruments
- Pressure Range: 2″ w.c. to 6″ w.c.
- Approximate Deadband: 0.07–0.25″ w.c.
- Switch Type: SPDT
- Media Compatibility: Air and non-combustible gases
- Port Connection: 1/8″ Female NPT
- Sensing Element: Large diaphragm
Applications
- Air handling unit (AHU) filter status monitoring
- Fan and blower proof-of-flow detection
- Duct static pressure control and alarming
- Building automation and HVAC control systems
- Pneumatic and low-pressure gas system monitoring
Why Choose the Dwyer 1638-5?
Dwyer’s Series 1638 pressure switches are a trusted choice among HVAC professionals for their robust construction and field-adjustable set points. The large diaphragm sensing element ensures reliable actuation even at low differential pressures, while the SPDT output provides maximum wiring flexibility. The 1/8″ FNPT connection makes integration into existing piping straightforward, reducing installation time on the job site.







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